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Y. I. Kim,H. J. Hyun,D. H. Kah,Heedong Kang,김홍주,김현옥,Kyeryung Kim,박환배 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.54 No.5
We designed and fabricated silicon PIN diodes on a 5-in. high resistivity (>5 kΩ·cm), (100)- orientation, n-type 380 μm-thick silicon wafer and developed a diode with an active area of 1.0 × 1.0 cm2. The signal-to-noise ratio (SNR) of the PIN diode with the 45-MeV proton beam of the MC-50 cyclotron at the Korea Institute of Radiological and Medical Sciences (KIRAMS) was measured to be 20.8 after being corrected for the minimum ionizing particle. The silicon diode was also exposed to the proton beam for the radiation damage study. The leakage currents of the silicon diode as a function of the reverse bias voltage were measured with a picoammeter before and after the proton beam irradiation. In this paper, we present an explanation of the radiation-induced detector deterioration and the SNR measurement for the manufactured silicon diode.
Studies of NO Adsorption on Proton-Irradiated MgO Surfaces
Jeonggil Lee,Jae-yong Kim,Jae-Kyun Jeon,Kyeryung Kim,Sang-pil Youn,Sangwha Lee,Youn Man Lee,Jeongha Kim,신관우 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.3
Recently, adsorption studies of gases for various adsorbents have been intensive because they are useful in probing the fine structure of the surface. Meso-sized MgO(100) powder was irradiated by a proton beam with a high energy of 35 MeV. Transmission electron microscope (TEM) investigations revealed no structural change of the MgO powders after irradiating with the proton beam. After proton beam irradiation, NO gas isotherm adsorption data were recorded from the same sample below the triple point (109.8 K). The results revealed that there was no hint of multi-isotherm step formation, which indicates the creation of an atomic layer of NO molecules. Instead, only a monolayer of NO molecules was obtained. It is understood that pre-existing unwanted impurities, such as water and carbon-related organic gases, hinder the formation of atomic layers in a regular fashion on the MgO powder surface. By comparing NO adsorption data from the pure and the proton-irradiated MgO samples, we were able to calculate the surface-related thermodynamic characteristics, including the 2-dimensional compressibility and the heat of adsorption. Recently, adsorption studies of gases for various adsorbents have been intensive because they are useful in probing the fine structure of the surface. Meso-sized MgO(100) powder was irradiated by a proton beam with a high energy of 35 MeV. Transmission electron microscope (TEM) investigations revealed no structural change of the MgO powders after irradiating with the proton beam. After proton beam irradiation, NO gas isotherm adsorption data were recorded from the same sample below the triple point (109.8 K). The results revealed that there was no hint of multi-isotherm step formation, which indicates the creation of an atomic layer of NO molecules. Instead, only a monolayer of NO molecules was obtained. It is understood that pre-existing unwanted impurities, such as water and carbon-related organic gases, hinder the formation of atomic layers in a regular fashion on the MgO powder surface. By comparing NO adsorption data from the pure and the proton-irradiated MgO samples, we were able to calculate the surface-related thermodynamic characteristics, including the 2-dimensional compressibility and the heat of adsorption.
Proton Irradiation and Hydrogen Diusion in Quasicrystals
Jae-Kyun Jeon,Jeonggil Lee,Euikwoun Kim,Yun-Man Lee,Sang-Hwa Lee,신혜민,Soo-Bin Choi,Sang-Pil Youn,Kyeryung Kim,Jae-Yong Kim 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.54 No.5
Ti-Zr-Ni quasicrystals are new candidates for hydrogen storage applications due to their capabil- ity of loading a large amount of hydrogen at reasonable temperature and hydrogen pressure. The technical applications, however, have been limited because of the presence of a thick oxygen layer, which must be eliminated prior to introducing hydrogen into a sample. To effectively remove the oxygen barrier and to enhance the capability of hydrogen absorption, we irradiated Ti39.5Zr39.5Ni21 quasicrystal ingots by using a proton beam at energy of 20 MeV, 15 mA for 30 minutes. The proton-beam-treated samples were exposed to a hydrogen pressure of 650 psi at 200℃ and the results were analyzed by monitoring the pressure change of the chamber. The main concerns were a careful measurement of the weight gain after hydrogenation and an estimate of the peak shifts in X-ray diffraction. An absorption of hydrogen was observed for the proton-beam-irradiated samples while little hydrogen loading was noticed for unirradiated ones. Our results demonstrate that proton irradiation may be used as a new technique that can effectively eliminate the oxygen barrier and enhance the rates of hydrogen diffusion. However, more systematic investigations regarding the role of the proton are required before applying the technique for practical applications. Ti-Zr-Ni quasicrystals are new candidates for hydrogen storage applications due to their capabil- ity of loading a large amount of hydrogen at reasonable temperature and hydrogen pressure. The technical applications, however, have been limited because of the presence of a thick oxygen layer, which must be eliminated prior to introducing hydrogen into a sample. To effectively remove the oxygen barrier and to enhance the capability of hydrogen absorption, we irradiated Ti39.5Zr39.5Ni21 quasicrystal ingots by using a proton beam at energy of 20 MeV, 15 mA for 30 minutes. The proton-beam-treated samples were exposed to a hydrogen pressure of 650 psi at 200℃ and the results were analyzed by monitoring the pressure change of the chamber. The main concerns were a careful measurement of the weight gain after hydrogenation and an estimate of the peak shifts in X-ray diffraction. An absorption of hydrogen was observed for the proton-beam-irradiated samples while little hydrogen loading was noticed for unirradiated ones. Our results demonstrate that proton irradiation may be used as a new technique that can effectively eliminate the oxygen barrier and enhance the rates of hydrogen diffusion. However, more systematic investigations regarding the role of the proton are required before applying the technique for practical applications.
D. H. Son,H. Park,H. J. Kim,H. O. Kim,Heedong Kang,Kyeryung Kim,S. Ryu,Y. I. Kim 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.3
The test result of a double-sided silicon strip detector (DSSD) obtained using a 45-MeV proton beam from the MC-50 cyclotron at Korea Institute of Radiological and Medical Science (KIRAMS) in Seoul, Korea, is presented. The manufactured DSSD consists of the double-sided silicon strip sensor and front-end electronics for signal readout. The implanted strips on the p-side are perpendicular to those on the n-side to provide two dimensional position information. The strip sensor has 512 readout channels on each side, and its size is 5.56 cm × 2.95 cm. For the sensor signal readout, we use a VA1TA-3 ASIC chip from Gamma Medica-Ideas, Norway, which provides analog outputs of 128 channels and a wire-OR'ed trigger output for every event. We present the details of the readout electronics systems and the beam test result of the sensor-electronics assembly. The test result of a double-sided silicon strip detector (DSSD) obtained using a 45-MeV proton beam from the MC-50 cyclotron at Korea Institute of Radiological and Medical Science (KIRAMS) in Seoul, Korea, is presented. The manufactured DSSD consists of the double-sided silicon strip sensor and front-end electronics for signal readout. The implanted strips on the p-side are perpendicular to those on the n-side to provide two dimensional position information. The strip sensor has 512 readout channels on each side, and its size is 5.56 cm × 2.95 cm. For the sensor signal readout, we use a VA1TA-3 ASIC chip from Gamma Medica-Ideas, Norway, which provides analog outputs of 128 channels and a wire-OR'ed trigger output for every event. We present the details of the readout electronics systems and the beam test result of the sensor-electronics assembly.
The Proton Energy Response of a LYSO Crystal
J.H so,김홍주,박환배,Heedong Kang,Kyeryung Kim,Minyong Lee,이상훈,김성환 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.3
We measured the energy response of a LYSO (Lu₂(1-x)}Y2xSiO5) crystal by using a proton beam. The LYSO crystal has good performances, such as a fast decay time, a high light output and radiation hardness and it is widely used for nuclear physics and medical imaging. The experiment was carried out in the MC-50 cyclotron at the Korea Institute of Radiological and Medical Sciences (KIRAMS) by using 35 and 45 MeV proton beams. Different thicknesses of Al degraders were used with the 35 and the 45 MeV proton incident energies to measure the light output response function of the LYSO crystal. The results were calibrated with a 137Cs γ-ray source for the different energy response of the LYSO and were compared with the proton energy calibrated by using the SRIM code, which is a well-known stopping-range calculation code. This is the first time for measuring the response function of the LYSO crystal with a proton beam.